Mueller signed on to co-star with Hilton's daughter Paris in new reality TV show The World According to Paris, but had to quit to check into rehab for help with her ongoing alcohol and drug problems.

Sheen's ex has now checked out of treatment and the Hilton matriarch insists she's doing "very well" but her friend really is in trouble.

She tells U.S. news show Access Hollywood Live, "This is a serious disease, alcohol and drug addiction... It's a disease like cancer.

"I know Brooke from Palm Beach, from years ago... I know her mother and father and I adore them. We formed this bond and when this whole thing happened... She has had addiction problems since she was 17... and when the whole thing went down in Aspen (I realised she had a problem)."

Sheen was arrested on Christmas Day, 2009 after reportedly attacking Mueller in a fight at their winter retreat.

Hilton admits she had her reservations about Mueller going public with her problems on the reality TV show: "I said, 'Are you sure that you would wanna do this - because this show is an open book...' And she said, 'I wanna share my journey... Maybe I can help somebody through this.'"

Wednesday night's episode of the reality show, which will air in America, features footage of an embarrassed Mueller coming to Kathy Hilton for help and weeping in front of her.

Photo Credits: PRN / PR Photos
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